With the increasing popularity of Internet commerce and network centric computing, businesses and other entities are becoming more and more reliant on information. Protecting critical data from loss due to human errors, software errors, system crashes, virus attack and the like is therefore of primary importance. Data archival systems are typically used in information systems to restore information in the event of a failure or error. Tape drives and/or write-able CD drives have historically been the storage medium of choice for data archival systems. Magnetic disk based archival storage systems have generally not been considered for long term storage because the lifetime of disks is relatively short and their power consumption is high compared to magnetic tape or write-able CDs.
Magnetic disks are typically used as primary storage for information infrastructures and as storage drives in personal computers, laptop computers, servers, and the like. A number of power saving techniques have been proposed for laptop computers. Software controlled power saving modes have been used to control power consumption during periods of inactivity. Adaptive algorithms which analyze access patterns to adaptively determine when to spin disks up or down to reduce power consumption. Such algorithms, however, usually focus on reducing the power consumption of laptop computers whose disks are specifically designed to spin up and spin down more times than required during the typical life expectancy of a laptop computer. Disks for desktops or servers are usually engineered to handle a limited number of starts and stops. Applying the same power conservation methods used with laptop computers to disk-based archival systems would shorten disk lifetime. Furthermore, these power saving techniques do not address the problem of checking or maintaining the integrity of data stored on disks for extended periods of time.
An archival disk-based data storage system that reduces power consumption, improves disk longevity and reliability, and maintains data integrity for extended periods of time is therefore needed.